Derived from CONFDEV-37031, if you search with the CQL query 'text ~ "search:"' you'll get a server error. This was a critical bug when the text field was being used by the Confluence Search screen UI but has been demoted now that it only affects the API.

See for an example:
https://pug.jira-dev.com/wiki/rest/api/content/search?cql=text~%22search:%22

where the error message in the 500 response is:

java.lang.IllegalArgumentException: INVALID_SYNTAX_CANNOT_PARSE: Syntax Error, cannot parse search::

//cc slancashire